stoichiometry

n. calculation of the quantities of elements (Chemistry)

Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).
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Noun
1. (chemistry) the relation between the quantities of substances that take part in a reaction or form a compound (typically a ratio of whole integers)
(hypernym) ratio
(classification) chemistry, chemical science

(n.)
The art or process of calculating the atomic proportions, combining weights, and other numerical relations of chemical elements and their compounds.
  

1. Ratios of atoms in a compound. 2. Ratios of moles of compounds in a reaction. 3. A branch of chemistry that quantitatively relates amounts of elements and compounds involved in chemical reactions, based on the law of conservation of mass and the law of definite proportions .